Light emitter chips, such as light emitting diode (LED) chips are solid state devices that convert electrical energy into light, and generally comprise one or more active layers of semiconductor material sandwiched between (e.g., vertically or horizontally) oppositely doped layers. When a bias is applied across the oppositely doped layers, holes and electrons are injected into the active layer where they recombine and generate light. Light is emitted from the active layer and multiple surfaces of the LED chip.
The active layer may be epitaxially formed on a substrate, such as a silicon (Si), silicon carbide (SiC), sapphire, gallium arsenide (GaAs), gallium nitride (GaN), etc., growth substrate, however, the completed device may or may not necessarily include the growth substrate. The diode region may be fabricated from non-organic or organic semiconductor-based materials. The light radiated by the LED chip may be in the visible or ultraviolet (UV) regions, and the LED chip may be used in conjunction with wavelength conversion material, such as phosphor(s) or lumiphor(s).
LED chips are increasingly being used in lighting/illumination products and applications, with a goal of providing a replacement for incandescent and fluorescent lighting. To accomplish the goal of replacing traditional lighting components with LED lighting components, LED lighting designers are faced with stringent dimensional, energy efficiency, and luminous flux output requirements. Such requirements have resulted in designers providing LED chips in arrays of various sizes and/or shapes.
Conventional LED products that utilize one or more LED arrays may require wire bonds to electrically connect the chips. The use of wire bonds in an array of chips is problematic, as wire bonds create a constraint on the density at which an array of chips can be provided. Wire bonds are also problematic in terms of blockage or absorption of light, as the metallic materials forming the wire bonds interfere with light. In some aspects, the wire bonds connecting to two topside contacts (e.g., two bond pads on a top surface), result in about a 1% to 2% loss in luminous flux per chip.
Providing SiC based chips in an array may add additional challenges, as SiC is light-absorptive and can result in blockage and/or absorption of light when adjacent chips are spaced too close. Thus, SiC chips also create a constraint on the density at which chips can be provided in an array. Beveling the sides of the chips may alleviate some of the absorption problems as beveling allows more light to escape the substrate, however; beveling can create more sideways emission that may then be absorbed by the SiC of a neighboring chip that is closely spaced. In some aspects, beveling the sides and/or crowding effects (e.g., the chips spaced too closely together) result in about a 1% loss in luminous flux per chip.
Accordingly, and despite the availability of various products in the marketplace, a need remains for brighter, more efficient, and more cost-effective LED components and/or methods, which make it easier for end-users to justify switching to LED products from a return on investment or payback perspective.